This invention relates to valves, and in particular to structure forming the internal porting in spool valves. In a spool valve, the valving action takes place between a movable element, sometimes called a spool, plunger or slider, and a fixed port in the side wall of the spool chamber in the valve body. In the particular type of spool valves to which this invention relates, the porting is in the form of an annular gap or groove that extends circumferentially around the entire side wall of the chamber in which the spool slides. An O-ring or other flexible sealing member or gasket mounted on the spool is shifted, by spool movement, from a position on one side of the port or gap, across the port to the other side.
This type of valving has been referred to as “across-the-gap” valving, because the sealing member on the spool moves across the fixed gap or port in the body. An example of such valving is shown in U.S. Pat. No. 3,819,152, in which a flexible sealing member on a movable spool valves the flow of fluid through a port in the form of a narrow annular gap extending circumferentially around the spool chamber. The port is formed by a stack of three interfitting elements having complex shapes, including a pair of annular elements having opposed circular internal edges that form the respective edges of the port, and an annular locator which spaces the two port edge-forming elements apart and at the same time aligns them axially.
The foregoing illustrates limitations known to exist in present valve devices. Thus it is apparent that it would be advantageous to provide an alternative directed to overcoming one or more of the limitations set forth above. Accordingly, an alternative annular port construction for valve applications is provided including the features more fully disclosed hereinafter.